The present invention relates to motor vehicle headlights, and more particularly to headlights having a mask, generally in front of the lamp or light source of the headlight, for masking or occulting light received from the light source.
An occulter, or mask, of this kind is well known for arresting some of the light radiation coming directly from the light source (the lamp), this light being directed firstly towards the cover glass of the headlight and secondly towards portions of the reflector which serve no optical purpose. One such mask is described in French patent specification No. FR 96 02387, which has a front face and upper, lower and side faces, which together cover the front part of the lamp of the headlight, and in which the side portions have ventilating windows.
These ventilating windows are formed by cutting out the sheet metal of which the mask is made, with reforming of the material outwardly in such a way that the latter projects out of the mask. Such aperatures do not constitute passages that are wide enough to give the required amount of ventilation for the interior of the mask and the walls of the mask. In addition, such apertures allow some of the light rays from the lamp to pass through.
Simply to increase the number of these windows, or apertures, in order to improve the ventilation would allow more light to pass through the mask to reach the non-optical parts of the reflector, and this will be detrimental to the efficiency of the headlight.
An object of the present invention is to propose a motor vehicle headlight in which the mask enables a large quantity of air to pass through it without being the source of optically undesirable leaks of light.
According to the invention, a motor vehicle headlight comprising a light source, a reflector and a mask, is characterised in that the mask comprises a set of elements which define in pairs, respectively, mutually facing faces such as to define between them passages through the mask, the said passages extending in directions which pass away from the light source.
Without in any way limiting the scope of the invention, the invention includes without limitation the following features, any one of which may, where practical, appropriate or desirable, be combined with any one or more of the others:
at least some of the passages are oriented in such a way that a light ray from the light source arriving in the said passage is unable to pass through the passage without performing at least two reflections on the mutually facing faces;
the said mask elements are thin elements which define, by each of their opposed sides, a face of an associated said passage;
the said mask elements of the said set of elements are generally flat in form and extend substantially parallel to each other;
the said passages lie in planes parallel to each other;
the said mask elements extend substantially at right angles to an optical axis of the headlight;
the said mask elements are in the form of annular rings, the axis of which is essentially parallel to the optical axis;
each said annular ring defines a surface facing towards the light source and approaching the optical axis when the annular ring is traversed in a direction from the rear towards the front of the mask;
the said annular rings consist of lamellae which face towards the light source, and each of which has a concave face facing towards the light source;
the said mask elements lie in planes substantially parallel to the optical axis of the headlight;
the adjacent edges of the said mask elements together define a geometric form;
the said adjacent edges are the edges which are closest to the light source;
the said adjacent edges are the edges furthest away from the source;
the said adjacent edges are anterior edges of the elements;
the mask includes a base wall, and in that the said elements have a root portion joined to the said wall;
the mask has an internal wall which is reflective to light, but only within a selected colour range, when the lamp is extinguished;
the mask has two fastening branches adapted to pass through the reflector, and a wire spring adapted to cooperate with two support elements, each of which is disposed at the end of a said branch of the mask, the wire spring being adapted to come into engagement on a rear face of the base of a lamp which is positioned in the base of the reflector;
the mask consists of a first member, having a lug for fastening to the rear of the headlight, and having an external diameter which is smaller than the diameter of a base opening of the reflector, and a second member having a diameter greater than the diameter of the base opening in the reflector, and in that the mask includes means for fastening the second member on the first member;
the mask consists of two members and a spring between the said two members, the spring urging the two said members away from each other, the two said members being provided with respective elements adapted to cooperate with each other so as to hold the said members fixed to each other while compressing the spring between them;
the said spring has the general form of an annular ring defining corrugations transverse to the mean plane of the annular ring;
the mask is made by a process including a step of hydroforming followed by a step of cutting;
the set of mask elements defining mutually facing faces consists of a set of annular rings stacked on a support structure.
Further features and advantages of the invention will appear more clearly on a reading of the following detailed description of some preferred embodiments of the invention, which is given by way of non-limiting example only and with reference to the accompanying drawings.